What are HVAC duct construction standards?

The HVAC Duct Construction Standards – Metal and Flexible is primarily for commercial and institutional projects. Rectangular, round, oval and flexible duct constructions for positive or negative pressures up to 10 in. water gage (2500 Pa). Standard procedures, methods, and equipment re-quired to properly balance both air and water systems.

What is the building pressure allowance for supply air duct SYS-TEMS?

Building pressure allowance for supply air duct sys-tems should be determined from building ventilation requirements taking into consideration normal build-ing infiltration. Allowance in the range of 5 to 25 Pa for building pressurization normally is used.

How to choose duct system pressure?

The choice of duct system pressure is becoming more dependent on energy costs, the ap-plication, and the ingenuity of the designer. The Static Regain Method" and the Total Pressure Method" have traditionally been used to design the higher pressure supply air systems.

What should a HVAC duct system designer consider?

The HVAC duct system designer is faced with many considerations after the load calculations are completed and the type of distribution system is determined. This manual provides not only the basic engineering guidelines for the siz-ing of HVAC ductwork systems, but also related information in the areas of: g. Duct Leakage h. Acoustic Considerations

What size duct should be used in a supply duct system?

Round spiral duct with an absolute roughness of 0.0003 in. will be used in this supply duct system. For the 80 in. of duct in section CF, and using an assumed velocity of 3200 fpm, it falls right on the closest stan-dard size duct diameter of 34 in. (in the chart of Figure A−1).

How much pressure should a commercial air duct have?

In recent years, most commercial HVAC supply air ductwork has been designed for a maximum pressure of 6 in. wg (1500 Pa) to save energy and operating costs. During the 1960s, systems designed at 10 in. wg (2500 Pa) were common with fan horsepower of 100 HP (75 kW) or greater.